Solo flight about 100 hours, stand-by more than a week, docked with the ISS about 30 days[1]

Apogee:

460 km[1]

Perigee:

350 km[1]

Inclination:

51.6 degrees[1]

The H-II Transfer Vehicle (HTV), also called Kounotori(こうのとり,Kōnotori, "Oriental stork" or "white stork"), is an automated cargo spacecraft used to resupply the Kibō Japanese Experiment Module (JEM) and the International Space Station (ISS). The Japan Aerospace Exploration Agency (JAXA) has been working on the design since the early 1990s. The first mission, HTV-1, was originally intended to be launched in 2001. It launched at 17:01 UTC on 10 September 2009 on an H-IIB launch vehicle.[5] The name Kounotori was chosen for the HTV by JAXA because "a white stork carries an image of conveying an important thing (a baby, happiness, and other joyful things), therefore, it precisely expresses the HTV's mission to transport essential materials to the ISS".[6]

Contents

Design1

Flights2

Evolution prospects3

HTV-R3.1

Lagrange outpost resupply3.2

HTV-X3.3

See also4

References5

External links6

Design

Structure

Inside view of the Pressurised Logistics Carrier section of HTV-1.

Canadarm2 removing unpressurised payload from HTV-2.

The HTV is about 9.8 m long (including maneuvering thrusters at one end) and 4.4 m in diameter. Total mass is 10.5 tonnes, with a 6,000 kilograms (13,000 lb) payload.[1] The HTV are comparable in function to the RussianProgress, EuropeanATV, commercial Dragon, and commercial Cygnus spacecraft, all of which bring or are planned to bring supplies to the ISS. Like the ATV, the HTV carries more than twice the payload of the Progress, but is launched less than half as often. Unlike Progress capsules and ATVs, which dock automatically, HTVs and American commercial crafts approach the ISS in stages, and are signaled by ISS crew or ground control to continue from one holding point to the next. Once they reach their closest parking orbit to the ISS, crew grapple them using the robotic arm Canadarm2 and berth them to an open berthing port on the Harmony module.[7]

The four main thrusters. Smaller attitude control thrusters can be seen at the right side of this view of HTV-1.

The intention of HTV's modularized design was to use different module configuration to match the mission requirement.[8] However, to reduce the development cost it was decided to fly the mixed PLC/ULC configuration only.

To control the HTV's attitude and to perform the orbital maneuvers such as rendezvous and re-entry, the craft has four 500 N class main thrusters and twenty-eight 110 N class attitude control thrusters. Both use bipropellant, namely monomethylhydrazine (MMH) as fuel and mixed oxides of nitrogen (MON3) as oxidizer.[9] HTV-1, -2, and -4 use Aerojet's 110 N R-1E, Space Shuttle's vernier engine, and the 500 N based on the Apollo spacecraft's R-4D.[9] Later HTVs use 500 N class HBT-5 thrusters and 120 N class HBT-1 thrusters made by Japanese manufacturer IHI Aerospace Co., Ltd.[10] The HTV carries about 2400 kg of propellant in four tanks.[9]

After the unloading process is completed, the HTV will be loaded with waste and undocked. The vehicle will then deorbit and be destroyed during reentry, the debris falling into the Pacific Ocean.[3]

Flights

HTV-2 departing Tanegashima spaceport bound for the International space station

Initially seven missions were planned in 2008-2015. With the extension of ISS project after 2015 through 2020, three more missions are planned, possibly replacing the tenth flight with an improved, cost-reduced version (HTV-X).[11]

As of March 2015, five subsequent missions are planned—one each year for 2015–2019[13] —one fewer total mission than had been planned in August 2013 at the time the fourth HTV mission was underway.[14]

Evolution prospects

HTV-R

As of 2010, JAXA was planning to add a return capsule option. In this concept, HTV's pressurized cargo would be replaced by a reentry module capable of returning 1.6 tonnes (1.8 tons) cargo from ISS to Earth.[22][23]

Further, conceptual plans in 2012 included a follow-on spacecraft design by 2022 which would accommodate a crew of three and carry up to 400 kilograms (880 lb) of cargo.[24]

Lagrange outpost resupply

As of 2014, both JAXA and Mitsubishi have conducted studies of a next generation HTV as a possible Japanese contribution to the proposed international manned outpost at Earth-Moon L2.[25][26] This variant of HTV is to be launched by H-X Heavy and can carry 1.8 tons of supplies to EML2.[25] Modifications from the current HTV includes the addition of solar electric paddles and extension of the propellant tank.[25]

To re-use the HTV's Pressurized Logistics Carrier (PLC) as much as possible, except adding a side hatch for late access cargo,

To replace the Unpressurized Logistics Carrier, Avionics Module, and Propulsion Module with a new Service Module

Instead of loading the unpressurized cargo inside the spacecraft, load them on top of the Service Module.

Re-using the PLC will allow minimizing the development cost and risk. Concentrating the Reaction Control System (RCS) and the solar panels to Service Module will allow simplifying the wiring and piping, to reduce the weight and the manufacturing cost. Loading the unpressurized cargo outside the spacecraft allows larger cargo, only limited by the launch vehicle fairing. The aim is to cut the cost in half, while keeping or extending the capability of existing HTV.[28]

As of July 2015, flight of HTV-X1(Technical Demonstration Vehicle) is proposed for 2021.[28]

This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and USA.gov, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for USA.gov and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.

Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.

By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.